Polly --

Leaf loss and branch dieback are indicators of root-rot. This is usually
caused by overwatering. (Once weekly is fine, so long as the tree needs
water once a week. Watering can and should vary with weather conditions,
soil mix, age of the tree, etc.)
You might want to consider repotting the tree -- removing any rotted roots
when you do -- in a soil mixture that promotes quick drainage. Prune below
the dead part of the branches. Keep the tree outside in partial sun for as
long as possible.

Good luck.

"Polly Spaulding" wrote in message
t...
I have a four year old orange tree which has flowered and fruited nicely
in
my greenhouse until this past summer, when it started losing leaves and
suffering some branch dieback. There is no evidence of insects or fungus.
The only difference in its care was that I had someone else watering it
for
me (weekly). Could overwatering explain these symptoms? Should I try
cutting it back? Presently it is leafless and seemingly dea... er,
dormant.
Thanks in advance-
Polly